The nation's most populous city also has the nation's largest homeless population, with 75,000, and like other high-rent cities, it has not been able to move the dispossessed to permanent housing nearly as fast as people are becoming homeless.

After being one of the most contentious issues on San Francisco's ballot last November, Proposition Q, which allows the city to remove homeless peoples' tents after issuing 24-hour notice and offering shelter, hasn't yet been used much.

The Denver lawsuit says the city, as part of an effort to clear the homeless from areas being gentrified, is violating their constitutional rights to be protected from unreasonable searches and seizures and to be treated equally under the law.

On Tuesday, the U.S. Department of Housing and Urban Development (HUD) published a final rule intended to ensure that all individuals will be guaranteed access to shelter programs according to their gender identity.